(1) Field of the Invention
The present invention relates to an improvement in a high speed semiconductor device known as a hot electron transistor (HET).
(2) Description of the Related Art
Examples of the related references in the field are as follows:
"Resonant Tunneling in Semiconductor Double Barriers", by L. L. Chang, L. Esaki, and R. Tsu, in Applied Physics Letters, Vol. 24, No. 12, Jun. 15, 1974;
Japanese Unexamined Patent Publication (Kokai) No. 58-3277 published on Jan. 10, 1983, Applicant: International Business Machines Corporation,
Inventor: L. Esaki, claiming priority based on U.S. application Ser. No. 280,141 filed on Feb. 5, 1982;
"Characterization of Double Heterojunction GaAs/AlGaAs Hot Electron Transistors", N. Yokoyama, et al. PROCEEDINGS OF THE IEEE INTERNATIONAL ELECTRON DEVICES MEETING, Dec. 1984, pp 532 to 535; and
U.S. application Ser. No. 754,416, filed Jul. 12, 1985 or European Patent Application No. 85401440.4, filed Jul. 15, 1985.
In recent years, due in part to advances made in molecular beam epitaxy (MBE) technology, there has been active development of semiconductor devices using heterojunctions. Among the same, considerable expectations are placed on HET's as high speed semiconductor devices, since hot electrons are used in the HET's as carriers and thus the transit time of the hot electrons through the base is drastically shortened (U.S. application Ser. No. 722,053, filed Apr. 11, 1985, U.S. application Ser. No. 796,406, filed Nov. 8, 1985, or European Patent Application No. 85400744.0, filed Apr. 16, 1985).
HET's prior to the present invention, however, contain the problems of high power consumption and low switching speed, because the lowest collector-emitter voltage for conducting current through the HET is relatively high.